Temperatura ambiente e concentrações séricas de cortisol em suínos em crescimento-terminação

Thirty-six castrated males and females Landrace x Large-White pigs (74 to 149 days of age) were randomly allotted to two environmental conditions: high temperature in a climatic chamber (HT; 22.2 to 32.8 °C) and comfort temperature in a conventional shed (CT; 17.6 to 26.6 °C), with night-and-day variations. Blood samples were weekly collected from animals of both HT and CT conditions for determination of serum cortisol levels. Cortisol levels of both sexes were not different, and there was no interaction with environmental temperature. Pigs of HT showed significantly higher average cortisol level (P<0.01) than the CT ones (7.06 and 4.82 mg/dL, respectively). Increasing in serum cortisol was continuous and linear (P<0.05) during the experimental period, suggesting the cortisol as a possible indicator of the heat stress in growing-finishing pigs.

Dinâmica populacional de Myzus persicae (Sulzer, 1776), Brevicoryne brassicae (Linnaeus, 1758) e Lipaphis erysimi (Kaltenbach, 1843) (Hemiptera: Aphididae) na região de Jaboticabal, SP

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Insect oral secretions suppress wound-induced responses in Arabidopsis

The induction of plant defences and their subsequent suppression by insects is thought to be an important factor in the evolutionary arms race between plants and herbivores. Although insect oral secretions (OS) contain elicitors that trigger plant immunity, little is known about the suppressors of plant defences. The Arabidopsis thaliana transcriptome was analysed in response to wounding and OS treatment. The expression of several wound-inducible genes was suppressed after the application of OS from two lepidopteran herbivores, Pieris brassicae and Spodoptera littoralis. This inhibition was correlated with enhanced S. littoralis larval growth, pointing to an effective role of insect OS in suppressing plant defences. Two genes, an ERF/AP2 transcription factor and a proteinase inhibitor, were then studied in more detail. OS-induced suppression lasted for at least 48 h, was independent of the jasmonate or salicylate pathways, and was not due to known elicitors. Interestingly, insect OS attenuated leaf water loss, suggesting that insects have evolved mechanisms to interfere with the induction of water-stress-related defences.

Role of Methyl Salicylate on Oviposition Deterrence in Arabidopsis thaliana

Plants attacked by herbivores have evolved different strategies that fend off their enemies. Insect eggs deposited on leaves have been shown to inhibit further oviposition through visual or chemical cues. In some plant species, the volatile methyl salicylate (MeSA) repels gravid insects but whether it plays the same role in the model species Arabidopsis thaliana is currently unknown. Here we showed that Pieris brassicae butterflies laid fewer eggs on Arabidopsis plants that were next to a MeSA dispenser or on plants with constitutively high MeSA emission than on control plants. Surprisingly, the MeSA biosynthesis mutant bsmt1-1 treated with egg extract was still repellent to butterflies when compared to untreated bsmt1-1. Moreover, the expression of BSMT1 was not enhanced by egg extract treatment but was induced by herbivory. Altogether, these results provide evidence that the deterring activity of eggs on gravid butterflies is independent of MeSA emission in Arabidopsis, and that MeSA might rather serve as a deterrent in plants challenged by feeding larvae.

Small antibody-like proteins with prescribed ligand specificities derived from the lipocalin fold

We demonstrate that the ligand pocket of a lipocalin from Pieris brassicae, the bilin-binding protein (BBP), can be reshaped by combinatorial protein design such that it recognizes fluorescein, an established immunological hapten. For this purpose 16 residues at the center of the binding site, which is formed by four loops on top of an eight-stranded β-barrel, were subjected to random mutagenesis. Fluorescein-binding BBP variants were then selected from the mutant library by bacterial phage display. Three variants were identified that complex fluorescein with high affinity, exhibiting dissociation constants as low as 35.2 nM. Notably, one of these variants effects almost complete quenching of the ligand fluorescence, similarly as an anti-fluorescein antibody. Detailed ligand-binding studies and site-directed mutagenesis experiments indicated (i) that the molecular recognition of fluorescein is specific and (ii) that charged residues at the center of the pocket are responsible for tight complex formation. Sequence comparison of the BBP variants directed against fluorescein with the wild-type protein and with further variants that were selected against several other ligands revealed that all of the randomized amino acid positions are variable. Hence, a lipocalin can be used for generating molecular pockets with a diversity of shapes. We term this class of engineered proteins “anticalins.” Their one-domain scaffold makes them a promising alternative to antibodies to create a stable receptor protein for a ligand of choice.